6种温带森林凋落量年际及年内动态

摘要

森林凋落物量及其组分因生态系统结构特征和环境变化而表现出明显的时间动态,从而影响森林生态系统物质循环和生态服务功能.连续6年观测帽儿山地区6种温带森林凋落物量及组份的时间动态、温度和降雨量等气象因子,旨在深入了解该地区森林生态系统的物质循环过程及调控因子.结果表明:6种森林的年落凋落量差异显著,平均值依次为:蒙古栎林(4.60 t/hm2)＞杂木林(4.21 t/hm2)＞硬阔叶林(4.03 t/hm2)＞红松林(3.95 t/hm2)＞杨桦林(3.89 t/hm2)＞落叶松林(3.85 t/hm2).各森林年凋落量的年际变化表现为“升高-降低”交替波动模式,但总体上呈上升趋势.凋落物各组份的年际变化不同,枝凋落量变化较为稳定;叶凋落量与凋落总量一致,升高-降低波动明显;繁殖器官及其他凋落量随林龄增加而增加.各森林凋落物量的年内变化呈单峰曲线波动,最大值出现时间因林型而异.枝凋落量在年内表现为双峰曲线模式波动;叶凋落量年内呈单峰曲线模式波动,并与凋落总量年内动态一致;繁殖器官与其他凋落量年内动态波动平缓,无明显凋落峰值.降雨量显著影响年凋落物量(P＜0.05),分别解释了凋落总量、叶凋落量90％、87％变化.平均温度、积温和总降雨量显著影响凋落量年内动态,总降雨量的影响作用最为突出.因此,除林分自身的生物学特性外,降雨是影响该温带森林凋落量年内、年际动态的重要因素.%Litter production and its composition in temperate forests show seasonal dynamics due to changes in the ecosystem structure and environment,which directly affect the nutrient cycling and ecological services in the ecosystems.In this study,we investigated seasonal dynamics in the litter production and its composition for six forest types in Maoershan region for six continuous years in order to reveal the factors driving the inter-and intra-annual variability of the litter production.The results showed that annual litteffall (t/hm2) decreased in the order of:Quercus mongolica stand (4.60) ＞mixed deciduous stand (4.21) ＞ hardwood stand (4.03) ＞ Pinus koraiensis plantation (3.95) ＞ Populus-Betula stand (3.89) ＞ Larix gmelinii plantation (3.85).There was a significant difference in total litterfall among the six stands.The litter production fluctuated interannually and showed an overall increasing tendency.The interannual variation in the litter composition depended upon its compoents:the litter production of woody tissues was relatively stable;that of foliages was consistent with the total litter production;and that of reproductive tissues and others increased with stand age.The production of total litter showed a mono-peak seasonal pattern for all the stands,and the occurrence of the peak varied with forest type.The litter production of woody tissues displayed a bimodal seasonal course;that of foliages was a mono-peak curve;and that of reproductive tissues and others was relatively stable intra-annually.Total rainfall significantly influenced the inter-annual litter production (P ＜ 0.05),and explained 90％ and 87％ of the variability in the total litter production and the production of woody tissues,respectively.Mean temperature,cumulative temperature and total rainfall significantly affected intra-annual variability in litter production,among which the effect of total rainfall was dominant.In conclusion,rainfall,in addition to the biological characteristics of the forests,was a key factor driving the inter-and intra-annual dynamics in litter productions.